MassDEP's Watershed Planning Program (WPP) conducts surface water monitoring and assessment activities throughout Massachusetts and reports its findings to the United States Environmental Protection Agency (USEPA) and the public as required by the federal Clean Water Act (CWA). Water quality assessments are conducted to evaluate the ecological and recreational ("fishable/swimmable") condition of Massachusetts’ surface waters.
Reporting Requirements
Sections 305(b), 314, and 303(d) of the CWA direct states to monitor and report on the quality of their surface waters and whether they support designated uses. WPP fulfills these monitoring and reporting requirements and evaluates the attainment of designated uses established in the Massachusetts Surface Water Quality Standards (314 CMR 4.00). Designated uses include aquatic life (such as fish, other aquatic life, and wildlife); fish consumption; public water supply; shellfish harvesting; primary (e.g., swimming) and secondary (e.g., boating) contact recreation; and aesthetics. Assessment and listing decisions are combined in biennial Integrated Reports to USEPA. To view MassDEP’s latest CWA sections 305(b), 314, and 303(d) decisions geospatially, use either WPP’s Water Quality Data Viewer (under the Integrated List of Waters view) or the MassMapper application (select “Regulated Areas” to access the most recent data layers for the MassDEP Integrated List of Waters).
Data Used in Assessments
Validated water quality monitoring data are provided by the WPP monitoring program (WPP Monitoring Data). Additionally, quality-assured data are provided from watershed associations and other outside groups (External Data Submittals). WPP uses these data, along with other state and federal agency data, to assess and report on surface water quality conditions in Massachusetts.
Assessment and Listing Methodology
The Massachusetts Consolidated Assessment and Listing Methodology (CALM) Guidance Manual (see Additional Resources below) describes how data are used to assess surface water quality conditions, and the process used to identify causes (e.g., “pollutants”) and sources of impairment. The CALM Guidance Manual also describes the categorization of the assessed waters as to whether they meet designated uses established in the Massachusetts Surface Water Quality Standards (314 CMR 4.00). Waters that are impaired for one or more uses due to pollutant(s) are listed on the 303(d) “List of Impaired Waters” (“303(d) List”).
The CWA requires states to submit reports on the designated use attainment status of their water bodies every two years. These "Integrated List of Waters" reports (IRs) combine the CWA reporting requirements of sections 305(b) (“Summary of Water Quality”) and the 303(d) List. Category 5 of the IR is assigned to surface waters on the 303(d) List that are impaired and require restoration plans, such as Total Maximum Daily Loads (TMDLs). The 303(d) List is subject to public review and comment and must be approved by USEPA.
2024 Consolidated Assessment and Listing Methodology Guidance
2022 Consolidated Assessment and Listing Methodology Guidance
2018 Consolidated Assessment and Listing Methodology Guidance
2016 Consolidated Assessment and Listing Methodology Guidance
2012 Consolidated Assessment and Listing Methodology Guidance
Statewide Statistical Reporting
In order to assess the quality of Massachusetts’ water resources, the MassDEP Watershed Planning Program (WPP) conducts both targeted and probabilistic surface water monitoring. Targeted monitoring approaches are by design limited to specific locations and typically cover a small percentage of the total waters in the state. To enable statistical reporting on the condition of all waters in the state, WPP uses probabilistic monitoring strategies to assess rivers, lakes, and estuaries. The overall goal of probabilistic monitoring designs is to provide an unbiased and statistically valid assessment on the condition of selected designated uses (e.g., Aquatic Life Use and Recreation Use) in all waters of the state and the potential stressors impacting those uses. The use of probabilistic monitoring is based on the principle that the quality of waters in a target population can be statistically estimated or inferred with a stated level of certainty by monitoring a random subset of the waters in the target population.
Rivers and Streams: In 2011, the Massachusetts Probabilistic Monitoring & Assessment Program (MAP2) was initiated with wadeable rivers and streams as the first water resource type assessed. The summary report for the MAP2 wadeable rivers and streams project is available here:
Technical Memorandum CN 529.0 - MAP2 Assessment of Wadeable River and Streams (2011-2015)
Lakes and Ponds: From 2016-2018, WPP conducted a statewide probabilistic monitoring project for MA lakes and ponds. The summary report for the MAP2 lakes and ponds project is available here:
MAP2 Lakes & Ponds report coming soon!
Estuaries and Coastal Waters: From 2020-2023, WPP conducted a multi-year probabilistic monitoring project for estuaries and coastal waters. A summary report will be published when available.
Macroinvertebrate Indices of Biotic Integrity (IBI)
MassDEP has developed macroinvertebrate Indices of Biotic Integrity (IBIs) to assess aquatic life conditions of multiple types of perennial, wadeable streams using biological indicators. IBIs were calibrated using a reference condition approach to identify characteristics of relatively undisturbed biological communities. Use of these IBIs will improve MassDEP’s diagnostic ability to identify degradation in biological integrity and water quality. Two IBIs were developed for high-gradient (riffle-dominated) streams in Massachusetts: one for the Western Highlands and another for the Central Hills. These two regions represent the natural variability of stream conditions found throughout the state. In addition, a single IBI was developed for low-gradient streams and is applicable statewide. These IBIs are included in the Massachusetts Consolidated Assessment and Listing Methodology (CALM) Guidance Manual and are used to determine the aquatic life use support status of wadeable streams for reporting under sections 305(b) and 303(d) of the Clean Water Act.
Four individual reports pertaining to the development and calibration of the IBIs for low- and high-gradient streams are available (see below). For additional information that supported the IBI development process, please contact WPP at this email address: dep.wpp@mass.gov.
Water Quality Assessment Reports
Water Quality Assessment Reports are no longer produced. For MassDEP’s latest Clean Water Act 305(b), 314, and 303(d) decisions, see Integrated Lists of Waters. Archived assessment reports by Watershed (WPP survey years 1997 through 2004) can be viewed here:
Water Quality Assessment Reports, Blackstone through Islands Watersheds
Water Quality Assessment Reports, Merrimack through Weymouth & Weir Watersheds